Dr. Manikantaswamy B M
You can get her checked physically by vet approximately around 30-35 days later from last mating, confirm the pregnancy with ultrasound scan (30-35 day is the minimum day of pregnancy when it can be identified by ultrasound).
If confirmed, then there are medication available orally they will help to abort the puppies.
Now it's not safe , also it's not necessary that every mating should have 💯 pregnancy. Confirm it before doing anything.